Topographic mapping using radar interferometry: processing techniques

Estimates of forest stand mean height using airborne LiDAR (Light Detection And Ranging) instruments have been previously reported with accuracies comparable to traditional ground-based measurements. However, the small area covered by a LiDAR sensor in a single aircraft overpass is a significant hindrance for large scale forest inventories. In comparison, airborne interferometric Synthetic Aperture Radar (InSAR) systems are also able to make estimates of surface height, but the swath coverage is often far greater, typically five or ten times that of the LiDAR coverage. A set of interferometric data takes was acquired by the ESAR airborne sensor over a managed pine plantation at Thetford Forest, UK. Scattering phase centre height estimates were made from two single-pass X-band acquisitions and polarimetric repeat-pass L-band acquisitions and compared with height estimates made from a separate LiDAR acquisition. The relationship between the scattering phase centre heights and stand top height is described, and the accuracy of stand top height estimates estimated from InSAR and LiDAR is quantified by the root mean square error (rmse). General yield class models by the Forestry Commission (UK) were used to estimate stand top height from a GIS database used for forest management.The longer wavelength L-band radiation penetrates deeper into the canopy than X-band and the scattering phase centre height is affected by both forest structural parameters (canopy density, understorey and gaps) and sensor parameters (look-angle and reduced coherence through temporal and volume decorrelation). Consequently, a simple translation of scattering phase centre height into stand top height gives noisy results for L-band, with observed rmse values between ±3.1m in the near range and ±6.4m in the far range. The X-band based top height estimates are more accurate with rmse between ±2.9m in the near and ±4.1m in the far range, which can be further reduced by an empirical incidence angle correction. Stand top height estimates from LiDAR achieved an rmse of only ±2.0m.The X-band scattering phase centre heights have also been related to mean stand height and are comparable with heights observed from the LiDAR sensor and field measurements. An rmse of ±2.5 m for the mean stand height estimates based the X-band data set was found. Finally, we briefly discuss error propagation from the use of a terrain model, here provided by the Ordnance Survey.

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“…Scattering phase centre height was estimated from the interferograms following eq. 3 by Madsen et al (1993).…”

Section: Digital Surface Model (Dsm) Generation 31 Insar Datamentioning

confidence: 99%

Observations of forest stand top height and mean height from interferometric SAR and LiDAR over a conifer plantation at Thetford Forest, UK

Balzter

Luckman

Skinner

et al. 2007

International Journal of Remote Sensing

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“…The images are properly registered, with a sub-pixel accuracy, and preprocessed to remove flat Earth interferometric phase [35] and to depurate the focused images from the atmospheric and nonlinear deformation contributions on a small scale (low resolution) [31]. Then, in any range-azimuth pixel, the m-th acquired image u m is given by the superposition of the signal backscattered by the targets located at the given azimuth and range coordinates, and at different elevation s. Then, the image signal, in the case of slow moving scatterers, can be expressed by [31] …”

Section: Tomographic Signal and 5d Scatterer Detectionmentioning

confidence: 99%

Extension of a Fast GLRT Algorithm to 5D SAR Tomography of Urban Areas

2017

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This paper analyzes a method for Synthetic Aperture Radar (SAR) Tomographic (TomoSAR) imaging, allowing the detection of multiple scatterers that can exhibit time deformation and thermal dilation by using a CFAR (Constant False Alarm Rate) approach. In the last decade, several methods for TomoSAR have been proposed. The objective of this paper is to present the results obtained on high resolution tomographic SAR data of urban areas, by using a statistical test for detecting multiple scatterers that takes into account phase variations due to possible deformations and/or thermal dilation. The test can be evaluated in terms of probability of detection (P D ) and probability of false alarm (P FA ), and is based on an approximation of a Generalized Likelihood Ratio Test (GLRT), denoted as Fast-Sup-GLRT. It was already applied and validated by the authors in the 3D case, while here it is extended and experimented in the 5D case. Numerical experiments on simulated and on StripMap TerraSAR-X (TSX) data have been carried out. The presented results show that the adopted method allows the detection of a large number of scatterers and the estimation of their position with a good accuracy, and that the consideration of the thermal dilation and surface deformation helps in recovering more single and double scatterers, with respect to the case in which these contributions are not taken into account. Moreover, the capability of method to provide reliable estimates of the deformations in urban structure suggests its use in structure stress monitoring.

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“…The main error sources of the navigation system that cause a height degradation in the final terrain model are the absolute height and the absolute roll angle errors [17]:…”

Section: Navigation System-induced Phase Errorsmentioning

confidence: 99%

Generation of high precision DEMs of the Wadden Sea with airborne interferometric SAR

Wimmer

Siegmund

Schwäbisch

et al. 2000

IEEE Trans. Geosci. Remote Sensing

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This paper describes how high-precision DEMs are obtained over the Wadden Sea using the AeS-1 airborne interferometric radar. The Wadden Sea is an intertidal zone along the coast which has height variations less than 5 m over 30 km and is free of vegetation. The resulting DEM has a grid spacing of 2.5 m and an absolute height accuracy of 5 cm rms, as verified by theodolite measurements. The paper describes the radar system, the processing techniques, the test area, the results, and the verification procedure.£ accepted for publication in

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Topographic mapping using radar interferometry: processing techniques

Cited by 264 publications

References 12 publications

Observations of forest stand top height and mean height from interferometric SAR and LiDAR over a conifer plantation at Thetford Forest, UK

Observations of forest stand top height and mean height from interferometric SAR and LiDAR over a conifer plantation at Thetford Forest, UK

Extension of a Fast GLRT Algorithm to 5D SAR Tomography of Urban Areas

Generation of high precision DEMs of the Wadden Sea with airborne interferometric SAR

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